1. Field of the Invention
The invention generally relates to a power measurement and monitoring technique, and more particularly, to a power monitoring technique for identifying the state of an electric appliance based on the feedbacks from users, such that the user can understand the power consumption of individual appliances conveniently.
2. Description of Related Art
Power monitoring devices (also referred to as electricity meters) are devices used for measuring and monitoring power consumptions of residential and industrial areas or electric appliances. A power company can sell electric power based on the power consumption information shown on an electricity meter, and a user can install an electricity meter at the main power supply or a power supply in his/her house or company to monitor the power consumption.
In recent years, energy saving and carbon reduction have become a hot topic in our society. Most electricity meters currently used by power companies are mechanical meters that can only display the total power consumption information of a house or building but cannot provide real-time power consumption at specific time or period. Thus, in many countries around the world, digital smart electricity meters (or smart meters in short) are being enthusiastically promoted for the construction of smart power supply networks (or smart grids in short). A smart meter can report the real-time power consumption to users and electric utility company. An electric utility company can further predict or manage the residential and industrial power consumptions during peak hours. To a user, a smart meter allows the user to understand the power consumption situation of his/her house, building or company at any time and can turn off those unused electric appliances to reduce electricity cost.
Taking household electricity consumption as an example, a conventional smart meter is usually installed at the main power supply in a house or a building. Thus, the user can only monitor the main power supply and obtain the power consumption information of the main power supply but not the detailed power consumption information of each electric appliance in his/her house or building. According to research results, 25% to 30% power consumption can be reduced if users are able to know the power consumption situation of each electric appliance in their houses or companies. Therefore, smart meter may integrate nonintrusive load monitoring (NILM) technique so that detailed power consumption information of individual appliances can be provided. However, smart meter with NILM feature may not be able to correctly detect different types of electric appliances due to the difficulty in collecting the power consumption feature data for a large amount of different appliances and new models. Besides, it is impossible to compare the power consumptions of the same electric appliance or different electric appliances having the same function in different places, houses, and building or to understand the efficiency of an electric appliance or determine the power consumption cause. As a result, the conventional smart meter may not be able to help users to understand the power consumption situation of each electric appliance in his/her house, manage the electric appliances with high power consumptions, determine the power consumption cause, or draw up a power-saving plan effectively.
If a user wants to monitor the power consumed by each electric appliance in his/her house and accordingly determines the power consumption cause, another solution is to attach a power consumption monitoring device or sensor similar to a smart meter to each electrical outlet in the user's house. A user may not be willing to install the power monitoring system described above since the user has to install a large number of power consumption monitoring device or sensors to every electrical outlet and spend cost and effort for the installation.